Preheat the oven to 180°C (350°F). Grease a 23 cm (9-inch) springform pan and line the bottom with parchment paper.
In a bowl, mix 200 grams of crushed digestive biscuits with 100 grams of melted unsalted butter. Press the mixture onto the bottom of the prepared pan. Bake for 10 minutes, then remove from the oven and let it cool.
In a large bowl, beat 500 grams of softened cream cheese with 200 grams of granulated sugar until smooth. Add 3 large eggs, one at a time, mixing well after each addition. Stir in 1 teaspoon of vanilla extract and 200 grams of sour cream.
Pour the cream cheese mixture over the cooled crust. Tap the pan gently on the counter to remove any air bubbles.
Bake the cheesecake for 45-50 minutes, or until the edges are set and the center is slightly jiggly. Turn off the oven, crack the door open, and let the cheesecake cool inside for 1 hour.
Remove the cheesecake from the oven and let it cool completely at room temperature. Then, refrigerate for at least 4 hours or overnight.
In a saucepan, combine 250 grams of fresh or frozen blueberries, 50 grams of granulated sugar, and 1 tablespoon of lemon juice. Cook over medium heat until the blueberries release their juices and the sauce thickens. Let it cool.
Once the cheesecake is chilled, remove it from the pan and spread the blueberry sauce on top. Serve chilled.